Sheet metal guides
Straight answers about getting custom metal parts made: files, materials, bending rules, welding, and finishes. Written by the people who cut, bend, and coat them.
Laser cutting
How to prepare a DXF file for laser cutting (without the back-and-forth)
A clean DXF gets you a faster, more accurate laser cutting quote. Here's how to set scale, close contours, clear junk lines, and send it right.
Laser cutting · 5 min readKerf in laser cutting: what it is, how wide it is, and when it matters
Laser cutting kerf is usually 0.1 to 0.3 mm, and the shop compensates for it. Here's when you can forget about kerf and when it changes your design.
Laser cutting · 5 min readLaser cut edge quality: what a good edge looks like and what affects it
A good laser cut edge is square and smooth with little dross. Learn what oxide, burr, and striations mean, and how to prep edges for welding and coating.
Laser cutting · 5 min readLaser cut metal signs: how to design one that cuts cleanly and lasts
How to design laser cut metal signs: picking the metal, keeping letters from falling apart, preparing artwork, and finishing for SA weather.
Laser cutting · 6 min readLaser cutting cost: what actually drives the price of your part
Laser cutting cost comes down to material and machine time. See how thickness, cut length, pierces, quantity, and nesting move your price.
Laser cutting · 5 min readLaser cutting file formats: which file should you send?
DXF is what the laser runs from, but DWG, STEP, PDF, and even a photo can get you a quote. Here's which file format to send for flat and bent parts.
Laser cutting · 6 min readLaser cutting tolerance: what's realistic and how to specify it
Laser-cut features in thin sheet are often quoted around ±0.1 mm, but bends, thickness, and part size change that. How to set tolerances that work.
Laser cutting · 5 min readLaser cutting vs plasma cutting: which one suits your part?
Laser is the better choice for sheet metal, fine detail, and clean edges. Plasma wins on cost for thick plate. Compare accuracy, edges, and price.
Laser cutting · 5 min readLaser cutting vs waterjet: how to choose for your part
Laser is faster and usually cheaper on sheet metal. Waterjet cuts cold and handles glass, stone, and rubber. Here's how to choose between them.
Laser cutting · 6 min readMinimum hole size for laser cutting: the thickness rule and its exceptions
Start with a hole diameter at least equal to the material thickness. Here's why small holes fail, plus spacing rules for edges, bends, and threads.
Laser cutting · 6 min readNesting in laser cutting: how your parts are laid out on the sheet
Nesting packs laser-cut parts onto a sheet to cut waste. Here's how it works, why part size and shape affect your price, and how to design for it.
Laser cutting · 6 min readTab and slot design for sheet metal: sizes, clearances, and mistakes to avoid
Tab and slot joints let laser-cut parts locate themselves for welding. Starting rules for tab size, slot clearance, corners, and coated parts.
Laser cutting · 6 min readWhat is laser cutting, and how does it work on sheet metal?
Laser cutting melts a fine line through sheet metal with a focused beam that follows your CAD file. How it works, what it's good at, and what to send.
CNC bending
Bend relief in sheet metal: where it goes and how big to make it
A bend relief is a small notch that stops sheet tearing where a bend meets an edge. Where you need one, how to size it, and which shape to use.
CNC bending · 6 min readBending aluminium sheet without cracking: alloy, radius, and grain
Aluminium cracks when the alloy is too hard for the radius or the bend runs with the grain. How to pick the alloy, radius, and direction to bend it cleanly.
CNC bending · 5 min readFlat pattern or 3D model: what to send for a bent sheet metal part
For bent parts, a 3D model lets the shop build the flat pattern with its own bend data. Here's when a flat DXF is fine and what each must include.
CNC bending · 6 min readHow close can a hole be to a bend in sheet metal?
Keep holes at least 2.5× thickness plus the bend radius from a bend, or they stretch into ovals. Here's a table in mm and fixes when space is tight.
CNC bending · 6 min readK-factor and bend allowance, with a worked example in millimetres
The K-factor sets where the neutral axis sits in a bend, usually 0.3–0.5. See how it drives bend allowance, with a worked example in mm.
CNC bending · 6 min readMinimum flange length: how short can a bent flange be?
A practical minimum flange length is about 4× the sheet thickness, so roughly 8 mm on 2 mm steel. Here's why, plus a table and fixes for short flanges.
CNC bending · 6 min readSheet metal bend radius: how tight can you go, and what should you specify?
A good starting bend radius is about 1× thickness for mild steel and soft aluminium, 1.5–2× for stainless. Here's why, and how to call it out.
CNC bending · 6 min readSheet metal bracket design: shapes, thickness, holes, and bends
Design sheet metal brackets around the bolts and the load: the right shape and thickness, holes clear of bends, long enough flanges. With a worked example.
CNC bending · 6 min readSheet metal enclosure design: from first sketch to a box that's easy to make
Design a sheet metal enclosure around what goes inside, where it lives, and how it opens. Material, construction, corners, sealing, and coating tips.
CNC bending · 6 min readSpringback in sheet metal: why bends open up, and what shops do about it
Springback is the angle a bend gives back after the press brake lets go. What causes it, typical amounts by material, and what it means for tolerances.
CNC bending · 6 min readWhat is CNC bending, and what does it mean for your part?
CNC bending folds flat sheet metal into accurate angles on a computer-controlled press brake. How it works, the bending methods, and how to design for it.
Fabrication
Fabrication assembly drawings: what to include so your job gets built right
A good fabrication assembly drawing shows the finished part, lists every piece, and marks welds and critical dimensions. Here's what to put on yours.
Fabrication · 5 min readMIG vs TIG welding: what the difference means for your parts
MIG is faster and cheaper per metre of weld. TIG is slower but neater and more controlled on thin sheet. Here's how to tell which your part needs.
Fabrication · 5 min readStainless steel weld discolouration: what heat tint is and how to remove it
The rainbow colours around a stainless weld are heat tint. They look bad and weaken corrosion resistance. Here's why it forms and how it's cleaned off.
Fabrication · 6 min readWeld distortion in thin sheet metal: why it happens and how to design around it
Thin sheet warps when welded because the weld shrinks as it cools. Learn what causes weld distortion and the design choices that keep parts flat.
Fabrication · 5 min readWelding vs bolting vs riveting: how to join sheet metal parts
Weld for permanent, rigid, sealed joints. Bolt when it must come apart. Rivet thin sheet or mixed metals without heat. Here's how to pick the right joint.
Fabrication · 5 min readWhat is metal fabrication? How flat sheet becomes a finished part
Metal fabrication is cutting, bending, joining, and finishing metal into a finished part or assembly. Here's how each step works and what drives the cost.
Materials
304 vs 316 stainless steel: when you need 316 and when 304 is plenty
316 adds molybdenum for better resistance to salt and chlorides. 304 is fine for most inland and indoor parts. Here's how to choose between them.
Materials · 5 min read3CR12 vs 304 stainless steel: which one does your part need?
3CR12 is the tough, cheaper utility grade for industrial work. 304 is for parts that must stay clean and good-looking. Here's how to choose.
Materials · 5 min readAluminium sheet grades explained: which alloy to use for your part
1050 is soft and easy to bend, 5052 is the all-rounder, 5083 is marine grade, 6082 is strong but bends poorly. Here's how to pick an aluminium sheet grade.
Materials · 5 min readAluminium vs steel sheet: weight, stiffness, corrosion, and cost compared
Aluminium sheet weighs about a third of steel but is about a third as stiff. Compare weight, strength, corrosion, fabrication, and cost before you choose.
Materials · 6 min readGalvanic corrosion: what happens when you mix metals, and how to stop it
Galvanic corrosion eats the weaker metal when two different metals touch in the wet. See which pairings are risky and how to design around them.
Materials · 5 min readMild steel vs stainless steel: which should your sheet metal part be made from?
Mild steel is cheaper and easier to work but rusts unless coated. Stainless costs more but resists corrosion. Here's how to choose for your part.
Materials · 5 min readSheet metal gauge to mm: a thickness chart, and how to choose the right thickness
16 gauge steel is about 1.52 mm, but 16 gauge aluminium is 1.29 mm. Use this gauge-to-mm chart, then learn how to pick sheet thickness for your part.
Materials · 6 min readStainless steel sheet finishes explained: 2B, BA, brushed and mirror
2B is the everyday mill finish, BA is bright, No. 4 is brushed and No. 8 is mirror. What each stainless sheet finish looks like and where it belongs.
Materials · 6 min readThe best metal for coastal areas in South Africa (and how to make it last)
Near the sea, 316 stainless or a properly coated part beats bare 304 and painted mild steel. Here's how to pick metal and finish for SA's coast.
Materials · 5 min readWhat is 3CR12? The utility stainless steel built for tough South African jobs
3CR12 is a low-cost utility stainless steel developed in South Africa. Learn what it's made of, where it's used, its limits, and how it cuts and welds.
Finishing & coating
Deburring sheet metal: why sharp edges matter and how they're removed
Deburring removes the sharp lips and slag left by cutting, punching and drilling. Learn which parts need it, the main methods and how to call it up.
Finishing & coating · 5 min readMasking for powder coating: threads, bores, earth points and how to mark them
Mask threads, close-fit holes, earth points and mating faces before powder coating. Learn what needs masking, how it's done and how to show it on drawings.
Finishing & coating · 6 min readPowder coating colours: how to pick a RAL code, gloss and texture
A good powder coating colour spec is a RAL code plus gloss and texture. How RAL codes work, which colours are popular and how to match an existing part.
Finishing & coating · 6 min readPowder coating galvanised steel: how to get a duplex finish that doesn't blister
You can powder coat galvanised steel, but zinc outgassing causes pinholes and blisters. Here's the prep, pre-bake and planning that make it work.
Finishing & coating · 5 min readPowder coating vs painting metal: which finish should you choose?
Powder coating gives a thicker, tougher finish for parts that fit in an oven. Paint wins on site, on huge parts and for touch-ups. Here's how to choose.
Finishing & coating · 6 min readTypes of metal finishing: a practical guide for sheet metal parts
Metal finishing covers deburring, brushing, blasting, powder coating, galvanising, plating, anodising and passivation. What each does and when you need it.
Finishing & coating · 6 min readWhat is powder coating, and is it right for your metal parts?
Powder coating is dry powder sprayed onto metal with static, then baked into a hard, even skin. How it works, what it's good at and where it falls short.
Ordering parts
Getting a metal part made from a sketch or a photo
No CAD? A hand sketch or photo can still get a metal part quoted and made. Here's what to draw, how to photograph it, and what details to include.
Ordering parts · 6 min readHow to get a sheet metal quote that's accurate the first time
An accurate sheet metal quote needs a usable drawing, material, thickness, quantity and finish. Here's what to send so the price you get is the price you pay.
Ordering parts · 6 min readSheet metal design checklist: 15 checks before you send it for a quote
Run these 15 sheet metal design checks on material, holes, bends, welds, coating, and files before you quote. Fewer questions, fewer remakes, better prices.